400: JSON is malformed: invalid character when trying to send binary data

[oaljabasini-calibroai]

Description

Hello,

I have a client that sends a pytorch model (after converting it to base64 string), for which I want my litestar server to read it and use it afterwards.

My client code:

import io
import torch
import base64
import requests

model = torch.hub.load('pytorch/vision:v0.10.0', 'alexnet', pretrained=True)
buffer = io.BytesIO()
torch.save(model, buffer)
buffer.seek(0)
model = buffer.read()
model = base64.b64encode(model).decode()
data = {"module_name": "module", "version_name": "version", "model": model}
response = requests.post("http://localhost:8080/api/v1/register", data=data)
print(response)

My server code:

from typing import Annotated
from dataclasses import dataclass
import io
import torch
import mlflow
import mlflow.pytorch
from litestar import Controller, post


@dataclass
class RegisterRequest:
    module_name: str
    version_name: str
    model: str

class MLFlowController(Controller):
    @post("/register")
    async def register(self, data: RegisterRequest) -> None:
        model = data.model
        # model = base64.b64decode(model)
        # model = torch.load(io.BytesIO(model))
        # mlflow.pytorch.log_model(model, f"{data.module_name}_{data.version_name}")

However, my litestar server is throwing the following error:

litestar.exceptions.http_exceptions.ClientException: 400: JSON is malformed: invalid character (byte 0)

I tried using dict[str, str] instead of creating a dataclass but it did not help. What should I do for my scenario? Note that sending a pytorch model is just an example; I might send a tensor or anything else that is not a simple class. Also I do not want to use multi-part requests for infra reasons).

URL to code causing the issue

No response

MCVE

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Steps to reproduce

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Screenshots

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Logs

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Litestar Version

2 (latest)

Platform

• Linux
• Mac
• Windows
• Other (Please specify in the description above)

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[provinzkraut]

Also I do not want to use multi-part requests for infra reasons).

But you are. Passing a dict to data will cause it to be form encoded.

From the requests docs:

data – the body to attach to the request. If a dictionary or list of tuples [(key, value)] is provided, form-encoding will take place.

https://requests.readthedocs.io/en/latest/api/#requests.Request

The error you are seeing is because you are telling Litestar to decode form encoded data as JSON.

You need to either send your data as JSON (e.g. by encoding it as a string before passing it to the data parameter, or passing your dictionary to the json parameter instead), or by setting the appropriate content-type in your handler so Litestar can decode it correctly: https://docs.litestar.dev/latest/usage/requests.html#content-type